java使用WatchService监控文件夹示例

通过java7提供的WatchService API 实现对文件夹的监控

package service;

import config.Config;
import java.io.IOException;
import java.nio.file.*;
import java.util.List;
import java.util.concurrent.TimeUnit;

public class WatchDirService {
  private WatchService watchService;
  private boolean notDone = true;

  public WatchDirService(String dirPath){
    init(dirPath);
  }

  private void init(String dirPath) {
    Path path = Paths.get(dirPath);
    try {
      watchService = FileSystems.getDefault().newWatchService(); //创建watchService
      path.register(watchService, 
      StandardWatchEventKinds.ENTRY_CREATE,
      StandardWatchEventKinds.ENTRY_MODIFY,
      StandardWatchEventKinds.ENTRY_DELETE); //注册需要监控的事件,ENTRY_CREATE 文件创建,ENTRY_MODIFY 文件修改,ENTRY_MODIFY 文件删除
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  public void start(){
    System.out.print("watch...");
    while (notDone){
      try {
 WatchKey watchKey = watchService.poll(Config.POLL_TIME_OUT, TimeUnit.SECONDS); //此处将处于等待状态,等待检测到文件夹下得文件发生改变,返回WatchKey对象
 if(watchKey != null){
   List> events = watchKey.pollEvents(); //获取所有得事件
   for (WatchEvent event : events){
     WatchEvent.Kind kind = event.kind(); 
     if (kind == StandardWatchEventKinds.OVERFLOW){
//当前磁盘不可用
continue;
     }
     WatchEvent ev = event;
     Path path = ev.context();
     if(kind == StandardWatchEventKinds.ENTRY_CREATE){
System.out.println("create " + path.getFileName());
     }else if(kind == StandardWatchEventKinds.ENTRY_MODIFY){
System.out.println("modify " + path.getFileName());
     }else if(kind == StandardWatchEventKinds.ENTRY_DELETE){
System.out.println("delete " + path.getFileName());
     }
   }
   if(!watchKey.reset()){ 
     //已经关闭了进程
     System.out.println("exit watch server");
     break;
   }
 }
      } catch (InterruptedException e) {
 e.printStackTrace();
 return;
      }
    }
  }
}

就是这么简单就可以对一个文件夹进行监控了。

完整带码地址:WatchServerDemo_jb51.rar

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